On Thursday, 17 December 2015 at 19:56:32 UTC, Jakob Jenkov wrote:
Hi guys,
I read from some of the other forum threads that D is being
criticized for not being usable for real time / low latency
systems because it has a GC.
First of all, such system are already being written in Java.
Google "Martin Thompson" and LMAX and you will see. Or Aeron
(also Java and Martin Thompson).
Second, when Java has been used to develop such systems, the GC
has been avoided as much as possible - which is even easier to
do with D than Java.
So, it's a load of BS that D's GC should somehow make it
impossible to make real time / low latency software.
Yes, it is a load of BS.
Andy Smith's talk from DConf 2015:
https://www.youtube.com/watch?v=0KBhb0iWsWQ
Summary - modern financial trading apps use multi-core machines
and shared memory via memory mapped files, and multi-core boxes
to achieve nanosecond latency. Compare to pre-2000 systems that
used single core and Tibco/RV networking. Remove the network,
remove the bottleneck.
Java does it using Chronicle (google Peter Lawrey). The other
twist is to reuse allocated flyweights to avoid triggering the GC.
Andy (unless I misheard) worked with/for Peter and has
reimplemented the same thing using D with comparable (or better?)
performance.
Even if D's entirely optional GC was on, its trigger could (I
would think) be avoid be similarly allocating once, and reusing
the object.
